Question

If ∆ABC ∼ ∆EDF and ∆ABC is not similar to ∆DEF, then which of the following is not true?
(a) BC ⋅ EF = AC ⋅ FD
(b) AB ⋅ EF = AC ⋅ DE
(c) BC ⋅ DE = AB ⋅ EF
(d) BC ⋅ DE = AB ⋅ FD

Answer 1

(c) BC ⋅ DE = AB ⋅ EF

∆ABC ∼ ∆EDF
Therefore,
$$\begin{gathered} \frac{AB}{DE}=\frac{AC}{EF}=\frac{BC}{DF} \\ \Rightarrow BC.DE\ne AB.EF \end{gathered}$$